Default SIM cards (aka preferred SIM cards) for calls, SMS messages and mobile data will be set up automatically to SIM card 1 by default in dual SIM Android phones. You may want to change the default SIM card for each task individually.
This Android guide explains how default SIM card works, and how to assign and use default SIM cards in dual SIM Android phones.
What is the default SIM card for calls, messages and mobile data in dual SIM Android phones?
When you insert two SIM cards into a dual standby Android phone, by default, the phone will use SIM card 1 as default SIM card for calls, texts and mobile data.
So, the default SIM card, or preferred SIM card, will be used for calls and messages, unless you specify a SIM card explicitly for a call or for a message.
For mobile data, you can use one and only one SIM card for it. But you need to specify the SIM card to be used for mobile data.
The default SIM card for calls can be different from that for messages or for mobile data.
The three default SIM card settings are independent to each other. In other words, the default SIM card for calls can be different from that for text messages.
Some Android vendors (e.g., Samsung) offer two SIM card buttons in phone app and messages app. So, you can use them before placing the call. This would overwrite the default SIM card settings.
But in stock Android, the Phone app does not have such buttons for you to choose SIM card. You have to set up the default one.
If you want to make both SIM cards always available at all times in a dual SIM dual standby Android phone, please check this guide.
How to assign default SIM card for calls, messages and mobile data in dual SIM Android phones?
As mentioned earlier, by default, the dual SIM Android phone will assign the SIM card in SIM card slot 1 as the default SIM card for all: calls, text messages and mobile data.
This may be not what you want.
For example, a lot of dual SIM phone owners use one SIM card for mobile data and the other for calls and messages.
To set up default SIM card for calls, messages and mobile data in a dual standby phone, you may open Settings app first.
In Setting, as shown below, tap SIM management.
In SIM management page, you can find at least two categories as shown below:
- SIM management.
- Preferred SIM for mobile data, calls and SMS messages.
These settings are available in all dual SIM Android phones. You many find some other additional settings added by the phone manufacturers.
Under SIM card management, you can
- enable and disable individual SIM card. You can temporally disable and enable any of the SIM cards.
- enter phone number for the corresponding SIM card. The phone number entered actually is just for your reference only.
- set color for each SIM card.
Please note, if you disabled the default SIM card, the system will NOT change your default SIM card to the other one. You have to assign it manually.
Under Preferred SIM for mobile data, calls and SMS messages, you can set the default SIM card for the corresponding features.
As mentioned earlier, you MUST assign one and only one SIM card for mobile data. If you do not want to use mobile data, you need to disable mobile data in Settings— Data usage to disable mobile data for the system. In almost all Android phones, you can also find the mobile data button in quick settings shade. You can enable and disable mobile data there.
For SMS text messages, in stock Android, you also must specify one SIM card as shown below.
However, for voice calls, in addition to two SIM cards, you have one additional option of “Always ask” to be used as default SIM card for calls as shown below.
If you choose always ask, you will be promoted to choose a SIM card before the outgoing call is placed.
How to use default SIM cards for calls, messages and mobile data in dual SIM Android phones?
The default SIM card for mobile data can only be changed manually. There is no quick switch or switch on-the-fly.
You need to disable mobile data in system settings, not SIM card settings, if you want to halt/pause mobile data usage.
Phone app in most dual SIM Android phones does not have SIM card options. In this case, the default SIM card settings will used.
If you chose Always ask as the preferred SIM card for calls, you have to choose the SIM card whenever you make calls.
Some Android vendors may offer additional options.
For text messages, it is a bit complicated.
As shown earlier, for text messages, you have to choose one of the SIM card as the default SIM card for SMS messages. You do not have the “Always ask” option for preferred SIM card for SMS.
Stock Android has such an arrangement because the stock Android Messages app has the option to specify SIM card for the outgoing text messages.
When you reply a text message, the SIM card will be chosen based on the origin of the original message. If it is to SIM card 2, SIM card 2 will be chosen automatically (you can manually change it if you want. Read on.) even if SIM card 1 was set as the preferred SIM card for SMS messages.
When you start a new text message, the default SIM card will be chosen as shown below.
In this example, it is SIM card 1.
Before typing your message, you can tap SIM card 1 icon to see the options of choose SIM cards as shown below.
For example, you can tap SIM card 2 to use SIM card 2 to send out this message.
In stock Android, you can only select SIM card for a new outgoing text messages:
- after select or type recipient; and
- before tying the message.
This will overwrite the preferred SIM card for text messages.
Can you set and use default SIM card for calls, messages and mobile data in dual SIM Android phones now?
If you have any questions or encounter any issues with the default SIM cards (preferred SIM cards) for calls, SMS messages and mobile data, please let us know in the comment box below.
For questions on Android Nougat (Android 7.0 and 7.1), please check Android Nougat guides page.
For questions on Android Marshmallow (Android 6.0), please check Android Marshmallow guide page.
For question on Android Lollipop (Android 5.0 and 5.1), please check Android Lollipop guide page.
For other Android questions or problems, please check Android 101 page.